Electrical protective alarm system



April 1l, 1944. H. M. LAFORD ELECTRICAL PROTECTIVE ALARM SYSTEM Filed May 6, 1939 2 Sheqts-Sheet 1 |523 JOEPZOO IN VENTOR. Ji'erberl' 777. eaford S Moed 72?@ ATTORNEY.

April 11, 1944. H. M. LAFORD ELECTRICAL PROTECTIVE ALARM SYSTEM Filed May e, 1959 2 Sheets- Sheet 2 INVENT OR. xcrber 711. aford BY fxaf/ ATTORNEY Patented Apr". 11, 1944 UNITED STATES iTENT OFFICE ELECTRICAL PROTECTIVE ALARM SYSTEM Herbert M. Laford, Bloomeld, N. J., assignor to Electro-Protective Corporation, Newark, N. J., a corporation of New Jersey Application May 6, 1939, Serial No. 272,084

9 Claims.

This invention relates to electrical' protective alarm systems, such as burglar alarm systems for mercantile premises.

Among the objects of the invention is an improved electrical alarm system of the type used in burglar alarm systems, and the like, which is foolproof in operation, easy to maintain in its eiiicient operating condition, and simple to test and supervise; such system using an extremely compact outdoor alarm housing for housing the batteries and the alarm sounding device which is connected through a cable to the interior of the protected premisesyand so arranged .that when the cable is cut or short-circuited, the alarm device is actuated and automatically set in operation by the battery in the outdoor housing; such system with an outdoor housing having an alarm sounding member in the form of .a plate-like structure which occupies only a negligibly small space Within the housing; such arrangement in which the outdoor housing is provided with an insulating housing lining serially connected in the protective wiring circuit of the system and so arranged'that'when the outdoor housing is moved to its open position, the lining is moved with it to expose the interior elements for easy inspection and servicing; such system combined with an electric power supply circuit which is energized from the standard commercial electric supply line and arranged to supply substantially all energy required for maintaining all the circuits of the protective system energized under protection on as well as protection ofi conditions While assuring that upon a failure of the commercial electric power supply, energy for actuating the alarm is supplied from the battery; such system with a commercial power supply circuit so arranged that on the occurrence of a trouble, the commercial power supply impresses on the protective system voltage which is suiiiciently high so as to deliver from the commercial povver supply circuit all the energy required for sounding the alarm and operate the protective system during the alarm condition; such system combined with a control switch is moved to the oii position on entering the premises, by the door key, for instance, for silencing the alarm and so arranged that the alarm is started if the control switch is moved to the on position on leaving the premises, if the protective wiring circuit of the system is not set for the protection on condition when leaving the premises; such system in combination with means for automatically resetting the protective system after a predetermined period if the alarm was started by an alarm condition which is removed or disappears soon after the-alarm was started, as well as an arrangement for securing a sequence of such resetting cycles and for stopping the alarm after a predetermined duration or a predetermined number of resetting intervals; such protective system having a protective Wiring system operative by a normal protective voltage current to perform the protective functions in combination with an arrangement for energizing the circuit with a current of a different character for selectively indicating the location of a trouble or fault on the system while assuring that the trouble indicating elements do not interfere with the normal operation and the setting up of the protective Wiring system; such protective system in combination with a multi-conductor cable for connecting the protective elements located in the outdoor alarm housing with the Wiring system extending through the protected premises in combination with a local energy source located in the outdoor housing, so as to make it impossible to defeat the protection by severing the multi-conductor cable between the housing and the premises; such system with a cable connecting the elements located in the protected premises with the elements located in the outdoor alarm housing in combination with a fuse so arranged in the outdoor housing that if the cable is short-circuited, the fuse will blow and disconnect the battery from the cable thereby assuring that the alarm is operated even if' the cable is short-circuited.

The foregoing and other objects of the invention will be best understood from the following description of exemplications thereof, illustrated in the accompanying drawings wherein Fig. 1 is a diagrammatic view of an electrical protective burglar alarm system exempliiying the invention in its protection on condition;

Fig, 2 is a circuit diagram of the protective wiring section of the system connected for the testing condition in combination with a modified indicator arrangement;

Fig. 2A is a diagram similar to Fig. 2 illustrating a modied form of indicator arrangement; and

Fig, 3 is a diagrammatic shovvingof four successive positions of the control cam mechanisms.

The principles underlying the invention will be explained in conjunction with a protective alarm system diagrammatically shown in Fig. l which exemplies the general arrangement of a burglar alarm protective system suitable for mercantile may be opened in the daytime during the normal j occupance of the premises, contactor I5 being, for instance, the spring contactor of the main entrance door into the premises. These guard elements I0, II, I2, I3, I4, I5 areinterconnected into a protective wiring circuit which is provided with a control unit 8, usually located inside the protected premises, and is connected by a leadcovered multiconductor cable to an alarm soundi ing unit 1 which is usually disposed on the exterior of the protected premises so that the sounded alarm will be noticed by the passing people, being mounted high up on a Wall, for instance, so that vit can be reached only by a tall ladder.

In the following specification and claims, the term protective wiring will reer to all the elements connected in the circuit of the protective system, which is generally a series circuit and includes Window foil lacing, screens, trap doors, and other wired units and associated switch and spring tamper contacts. The term protective wiring as used herein is also understood to include all equivalent structures, such as those used for protection of safes, bank vaults or the like.

The alarm unit is formed of a rugged metal housing, its structural arrangement being shown in Figs. 1 to 3. The alarm housing consists, in addition to the outer housing structure indicated, in Fig. 1, at 20, of an interior metal lining 2l insulated from the exterior housing 2f). Inside the alarm housing is mounted a local energy source, such as a dry cell battery I1, an alarm device, such as a bell I8, an alarm relay A with contacts 25, 2S, a locking relay L with contacts 21, 28, 29, 30, and the various wiring elements referred to hereinafter. The alarm housing is protected against tampering by the usual bolt and pry-off tampers indicated schematically at 23.

The control unit 8 is formed of a cabinet usual.- ly mounted in the interior of the guarded premises, and houses a manually operated on-oiltest control switch 50 with contacts SWI, SW2, SW3, SW4, and SW5 a milliammeter GI, and various other elements used for controlling and supervising the protective wiring circuits which interconnect through a lead-covered multicenductor cable the elements ci the exterior alarm housing with the elements of the guarded premises. The control unit 8 also houses a resetting mechanism including a reset motor 52 with reset cams 53, 54 and earn controlled contact-ors CI, C2, C3, C4, C5 for' automatically controlling the resetting of the protective system following the occurrence of an alarm condition as will be explained hereinafter, and a trouble-locating switch arrangement 5I for enabling quick and simple location of the point of the protective system which started the alarm or is defective. In addition, the control unit 8 is provided with a tamper switch 83 arranged to be connected in series with the protective wiring during the protection on condition so that upon opening the door of the control unit during the protection yto a minimum the drain of current from the local battery I1 of the alarm housing 20. In addition, the power unit 9 supplies energy for operating the automatic resetting mechanism, the

fault locating arrangement and for other auxiliary service, such as the pilot lamp illumination. The power supply unit may be formed of a transformer 35 having a primary winding connected through fuses 32 to terminals 3I leading to a standard volt A. C. supply line. The transformer 35 has a low voltage transformer winding 36 which supplies through a copper oxide rectifier bridge 31 a rectied D. C. current of low voltage across the terminals of a ltering condenser 4I which are connected in series with the current limiting resistors 42, 43, by way of leads of the multiconductor cable and fuse I 6 to the terminals of the battery I1 within the alarm housing 1.

In a practical installation of the type shown in Fig. 1, the relays and the other elements of the protective system are arranged and designed for operation from a nine volt supply source and the transformer winding 36 with the rectifier 31 and the associated filtering condenser 4I and series resistors 42, 43 are so arranged and adjusted that normally substantially no current flows into or out of the battery I1. The transformer 36 is, for instance, designed to deliver an output voltage of about 12 volts and the resistors 42, 43 are dimensioned to maintain across the battery I1 la voltage of about 9 volts, resistor 43 being adjustable so as to adjust the power supply circuit to the condition of 0 current battery drain from the battery. As a result, failure of the external power supply from the power unit 9 does not affect the operation of the protective system, but under normal conditions the local battery I1 serves only as a standby source, and the power supply unit 9 serves as a principal source of energy for the protective system. In addition, the transformer 35 has also a high voltage secondary winding 45 which, as described hereinafter, is used in connection with the trouble locating switch arrangement 5| for locating trouble points of the protective system, series resistance 46 preventing inadvertent short circuiting of the transformer winding.

'I'he cooperative relationship of the various elements of the protective system will now be described for a normal protection on condition, for instance, when the premises have been closed for the night, and the elements of the system are connected to sound an alarm in case an attempt is made to enter the protected premises or to tamper with the system. In Fig. 1 the heavy line circuit shows the protective wiring connections during the protection on condition, the manual control switch 50 being in the on position and the trouble locating switch 5I in the oi position. For the sake of clarity, the auxiliary connections of the protective wiring to the auxiliary power supply unit 9 are not shown in heavy lines, but whenever in the subsequent description general reference is made to the flow of current through the protective wiring, it is uning tampers 2.3,

derstood that the current is normally supplied by the power unit 19 andnot tby the local .battery IFI.

l'n the protection on condition, the alarm relay A is serially connected and energized by current owing in the protective wiring circuit which may be traced as follows:

From the positive terminal of battery I1, through the actuating coil of the alarm bell I8, resistor 22, alarm housing lining 2l, alarm housby way of a cable conductor lto the closed contacts SW1 of the manually controlled switch .5D in the control unit, upper closed contacts TSI of the trouble locating switch I, through the wiring conductor 66 of the live protective loop including loop elements IB, II, back through wiring conductor B1, upper closed contacts TS2 of trouble locating switch 5I, in the .control unit, rheostat 1I, -milliammeter 5I, control cabinet door tamper contacts 63, `upper closed contacts SW3 of control switch 50, through a cable conductor to the lactuating coil of the alarm relay A; and continuing therefrom back through a cable conductor to the lower closed contacts SW4 of the control switch 50 in the control unit, wiring conductor 68 of the grounded protective loop including connectors I4, lacings I2, to conductor 69 and ground 15, and continuing through a grounded conductor 1E! passing the control unit, along the grounded cable conductor to `the grounded outer alarm housing 2 and therefrom .by way of the closed front contacts of the alarm relay armature 25 to the negative termina1 of the battery l1. In addition, the actuating coil of the locking relay L is energized in parallel with the bell I8' through a circuit leading, from the positive bell terminal connection, by Vway of fuse I6 through a cable conductor to the closed cam contacts CI of the resetting mechanism in the control unit 8, closed contacts SW2 of the manual control switch 5U 'back through the cable and the coil of the locking relay L to the other Iterminal connection of the bell I 8.

The alarm relay A, the locking relay L, and the bell IB and the associated circuits are so designed and proportioned and the current nowing through the protective wiring is so adjusted by the rheostat 'II that under normal protection on" conditions, only the alarm relay A is suf- -iiciently energized for keeping its armature front contacts 25 closed while the 'bell I8 and the locking relay L receive insuiicient current for sounding the bell or actuating the locking relay L. The milliammeter 5i facilitates the adjustment of the normal protection on current ow condition. In a practical installation, the current flowing in the wiring under normal protection on conditions is adjusted to l0 milliamperes. With the protective wiring `circuit so maintained in the protection on condition, the occurrence of a break or a cross in the protective wiring of the premises will bring about the de-energization of the alarm relay A in the alarm housing and instantaneous release of its armature from its normal closed front-contact `position tothe alarm closed back-contact 25 position. In the closed back-contact 26 position, the armature 25 ofthe alarm rela-y connects the bell I8 and the parallel locking relay L circuit directly across the full voltage of the battery I1, and thereby energizes the bell I8 and the locking relay L with suiicient current for instantaneously starting the sounding of the alarm bell I8, and for actuating the locking relay contacts 21, 28, 29, 30 to their front contact positions. Resistor 22 connecting the `alarm housing lining 2I to the bell lead is proiISIS portioned so 'as to .enable the silencing .of the bell `I8 .by `the key .shunt .switch 8l when -a .cross or short ,circuit occurs between the lining 2.I and the outer housing 2'0.

Under the protection on conditions described above, the energized position of the locking re.- lay L, establishes at its closed front contacts 27, 28, 29, 30 the following operating circuits:

Its closed front contacts 21 complete a hold- 'ing circuit for the locking relay L so as to retain its contacts locked in the front contact position and at the same time maintain itself as well as the bell I8 fully energized for .continuously sounding the alarm, even if the fault condition of the protective wiring disappears imme- .diately following its occurrence; its closed :front contacts 2B short circuit `the series resistor 43. in the 12. volt rectied power supply circuit so .as to draw the electric energy required for sounding the alarm and keeping the locking relay L in the locked position mainly from the power supply unit 9 and thus preserve the charge of the battery 'il its closed front contacts 29Ucomplete a signalling circuit for lleads 3| to the police headquarters for transmitting thereto an alarm; and its closed front contacts 35 energize the reset motor 52 and start the automatic resetting cut-oil mechanism which is combined with the control unit 8.

The automatic resetting mechanism comprises the reset motor 52 which drives through a shaft 55 rotary cams 53, 54 which operate through cam followers 55, 51, cam contactors CI, C2, C3, C-i, C5 arranged and operating in the way shown in Fig. l. and in their position diagrams shown in Figs. S-A-B-C-D. The resetting motor 52'may be of the self-starting synchronous type, and, as shown in Fig. l, may be energized from the volt transformer winding 35 so as to rotate the cams, for instance, in clockwise direction ind-.icated in Fig. 3, at the rate of one complete revolution per hour. Depending upon the particular requirements, such one revolution cam cycle may be arranged to have a dilierent period.

Fig. l and Fig. 3A show the normal protection on positions of the resetcams 53, 5A before the reset motor 52 is started 'by the occurrence of an alarm condition during protection on conditions. In this normal position of the reset mechanism, the follower cam 51 is held in the released position within a notch 15 of the cam 54 holding open its blade contacts C4, C5. A5 soon as the reset motor 52 is started by the occurrence of an alarm condition, the initial rotary motion imparted to the cam 51! lifts its follower cam 51 from the notch l5 to close its contacts Cil, C5. The closed cam contacts C4 are connected in parallel to the motor starting contacts 3i) and maintain the resetting motor 52 energized as long as the follower 51 rides on the raised outer periphery of the cam 54 extending between its notches 15, 18, and the closed cam contacts C5 complete an energizing circuit to the pilot 'lamp 5? of the control unit to indicate the occurrence of an alarm condition on the system.

In a prac-tical protective system of the type shown in Fig. 1, the cam 54 is provided, for instance, with three notches 15, '1.18, 1gb that are spaced vby about l/3 of the cam periphery corresponding to a time interval of about 20 minutes., or one third of the hour cycle of a complete cam rotation. These intervals may. of course, diiler in diierent systems.

Cam 53 is provided with a similaiset of three notches 15, 11 spaced by a 20 minute interval. The notches 16, 11 of cam 53 are located slightly in front of the corresponding notches of cam 54, so that shortly before the reset motor 52 returns the cams 53, 54 to the normal protection on starting position, shown in Fig. 3A, the follower S of cam 53 is lifted out of its cam notch 15 and closes at its blade contacts Cl the normal protection on energizing circuit for the locking relay L, while opening its blade contacts C2, C3.

The protective system provided with the resetting mechanism arranged in the way described above in connection with Figs. 1 and 3 will operate as follows:

In the normal protection on condition of the protective system the reset motor is de-energized and the reset cams 53, 54 with the associated cam contacts CI to C5 are in the positions shown in Fig. 1 and Fig. 3A.

Upon the occurrence of a break or short circuit or, in general, any interference with an element of the protective wiring, the alarm relay A in the alarm housing will be deenergized and actuate its armature 25 into engagement with its back contact 26 thereby energizing the locking relay L and the alarm bell I8 to sound the alarm and bring the locking relay contacts 21, 28, 29, 35i to the locked front contact positions. The closure of the locking relay contacts 30 energized the reset motor and starts the rotation of the reset cams 53, 54. The initial rotary motion of cam 54 lifts the follower 51 out of the cam notch 15 on to the raised periphery of the cam 54 to light up the alarm pilot lamp 60 at its closed camcontacts C5, and to maintain the reset motor energized at its closed cam contact-s C4. The circuit conditions so established will be maintained as long as the two cam followers 56, 51 ride along the raised peripheries of the rotating cams 53, 54 and the alarm will continue to sound during the 19 minute interval until the rotating cams 53, 54 reach position Fig. 3B. In this position, the cam contacts CI, C2, C3 are released by notch 11 and break at the open cam contacts Cl the holding circuit for the locking relay L and complete at the closed cam contacts C2, C3 an energizing circuit from the battery terminals to the alarm relay A, and thus silences the alarm.

Immediately thereafter, for instance, one minute later and minutes after the reset motor was started, the continuing rotation of the cams 53. 54

actuates the follower 56 to restore its contacts CI, C2, C3 to the position of Fig. 3C and releases the follower 51 into the shallow notch 18 of the cam 53 in the way shown in Fig. 3C, so as to break at its cam contacts C4 the energizing circuit to the reset motor `52 and thereby stop the motor and the rotation of the cams 53, 54 while keeping at its closed contacts C5 the pilot lamp 60 lighted for indicating that an alarm condition occurred on the system.

In this way, the resetting mechanism reestablishes completely the protection-on condition of the protective wiring if the alarm was caused by a transient condition which disappeared or was removed during the 20 minutes required for the cams 53, 54 to rotate from the starting position shown in Fig. 3A to the first ZO-minute interval position shown in Fig 3C. The occurrence of any subsequent transient alarm conditions cause this cycle to be repeated while the cams 53, 5-4 are advanced to their next notch positions, thus allowing a total of three about ZO-minute alarm period cycles, in the specic system shown in Fig. 1.

As a result, the occurrence of transient alarm conditions automatically limits the sounding of the alarm to a 20-minute period and after the lapse of the 20 minute alarm period the normal protection-on protective wiring conditions shown in Fig. 1 are automatically restored by the resetting mechanism. However, by providing the cam 54 with shallow notches 18, 13b, the associated lamp lighting cam contacts C5 keep the pilot lamp 60 illuminated until the system is manually restored to the fully normal condition, thus assuring that the owner of the premises is apprised of the occurrence of an alarm condition.

If the reset motor 52 is started by an alarm condition which is not removed within the resetting interval, as determined by the reset arrangement, the alarm would be silenced only momentarily at the end of each resetting interval, for instance, after each 19 minute period, and would continue to ring for a full one hour period while the reset motor continues to rotate its cams 53 to bring them to the position shown in Fig. 3D. Thus, if the alarm condition persists after a 20 minute alarm sounding interval during which the reset motor has rotated the cams 53, 54 from the position shown in Fig. 3A to the position shown in Fig. 3C, the persistence of the alarm condition instantaneously again de-energizes the alarm relay A, thereby again closing its front contacts and reestablishing the holding circuit which locks the relay L in the' locked condition in which its closed contacts reenergize the resetting motor 52 so as to continue its rotation for another 20 minute interval to repeat the cycle of operations performed during the first alarm sounding interval.

Should the alarm condition persist for the full timing period as determined, for instance, by the 60 minute period required for one revolution of the cams 53, 54, the reset motor 52, as it approaches its stop position, for instance, 59 minutes after its original start, will bring the resetting cams 53, 54 to the position shown in Fig. 3D. In this position, cam 53 opens at its contact Cl the holding circuit for the locking relay L and re-energizes at its closed contacts C2, C3 the holding circuit for the alarm relay A thus silencing the alarm. At the same time, the follower 51 is released into the shallow portion 19 of the starting notch 15 of cam 54 so as to open only the motor venergizing contacts C4 thereby stopping the motor while keeping its lamp energizing contacts C5 closed so as to indicate by the lighted pilot lamp 60 the occurrence of an alarm condition. The alarm is thus silenced or cut-out, and the motor is stopped in the cam position shown in Fig. 3D about one minute away from its starting position shown in Fig. 3A. The protective system remains in this cut-out condition until the manual control switch of the control unit is moved from the on position shown in Fig. 1 to the off position in which it breaks the contacts SWI, SW2, SW3, SW4 and completes at contacts SW5 an energizing circuit for the motor which turns it for about one minute until the cams 53, 54 are moved from its Fig, 3D position to its normal protection on starting position shown in Fig, 1 and Fig. 3A. Similarly, if the resetting mechanism had been retained in an intermediate position, for instance, that shown in Fig. 3C as a result of the occurrence of a momentary condition which brought about only a 20 minute alarm, the party returning on the premises and noting by the lighted pilot lamp that an alarm condition occurred on the system will fully restore the reset mechanism and the circuits of the system by pressing the manual resetting switch to the off position and thereby actuate the motor to return the cams to the position shown in Fig. 3A in which the resetting motor and its mechanism is in its starting position and the pilot lamp is extinguished. The fully normal protection on condition is then restored by returning the manual control switch 58' to its on position.

In order to enable an authorized person to enter the protected premises without starting the alarm, there is provided in the entrance door to the premises a key operated Switch 8| which in the closed position places a shunt around the part of the live protective wiring loop which includes the break contacts of the main entrance door and other removable attachments, such as windows, in such a way that they may be opened without aiecting the current flow conditions through the alarm relay A and the other parts of the protective wiring.

As shown in Fig. l, the key shunt switch #8| has its contacts connected parallel to the cam contacts C2 so that when the key switch 8| is closed, it provides a shunting by-pass from the positive battery terminal through fuse I6, resistor 84, closed key shunt switch 8| to the closed control switch contact SW3, which by-passes the part of the live protective loop extending from the positive side of the battery, through bell I8, resistor 22, alarm housing lining 2 I, alarm housing tampers 23, control switch contact SWI, trouble locating contact TSI, the live protective loop including the main door break contacts I5, back through the loop conductor 61, milliammeter 6| tothe control switch contact SW3. Upon closure of the key shunt switch 8|, the main door with its main door contact break I as well as the other protective break elements included in the shunted live loop, may be opened without sounding the alarm.

Upon entering the premises, the authorized party opens the control unit, and operates its main control switch 58, which is usually arranged in the form of a key switch actuable to either the on, o or test positions, to the ofi position, and thereby establishes the protection off circuit conditions. This opens at contacts SWI,

SW3, SW4 the circuits to the live loop conductors B6, 61 and to the grounded loop conductors 68, and at the contacts SW2' the holding circuit for the locking relay L is opened, the tampers contact switch 63 being in the downward, open door, position. At the same time, there is completed at the on position of contacts SWS an energizing circuit for the reset motor so as to return the reset mechanism to its starting position shown in Fig. 3A.

In addition, the control switch 56 establishes in its downwardly shown off position, a holding circuit for the alarm relay A leading from the positive battery terminal by way of fuse I6, resistor 84, closedV key shunt switch 8|, coil alarm relay A, and the closed contacts 82, 83 associated with contact blade SW4, to the negative battery terminal. The resistance 8'4 included in this protection o alarm relay holding circuit is so chosen as to energize the relay with its normal holding current, 10 milliamperes, for instance. Relay A remains thus energized and keeps the alarm silent. Negligible energy is consumed in this protection oli or daytime condition, and' only the power supply' circuit 8 delivers the current for thel alarm relay circuit.

` If on arriving onthe premises, the authorized party findsv the alarm pilot lamp St lighted, indicating; that an alarm condition existed during the protection on period, he has to locate the cause of the alarm condition and see to it that it is' removed. The trouble locating arrangement combined with the protective system of the invention greatly simplifies this task.

In the form shown in Fig. 1, the trouble locating arrangement utilizes the trouble locating switch 5I and a series of neon lamps, such as 85, 86, 8l connected at diierent points of the protective wiring loops between live and grounded portionsv of the loops. For instance, neon lamp 86 is: sho-wn connected between the main door switch I5 and the ground conductor 69; lamp 86 between the: conductor leading from the live lacing Io and the conductor leading from the grounded lacing I2; lamp-` 8l between the live loop conductor 61 andthe grounded loop conductor 68. Depending upon the degree ci supervision desired and the location andV length of the protective loops, any number of such trouble indicating lamp units may be provided.

In practica-l protective systems of the invention, neon lamps are used as such trouble indicating units. Such lamps do not draw any current or energy, and act as perfect insulators as long as the voltage applied to the terminals of the lamps is below 'their break-down voltage. As a result, their presence on the protective system which, i-s operated with lower voltage does not interfere with its operation and does not in any way impair the effectiveness of the protection rendered by the protective wiring unit. Practical l neon lamps suitable for protective Systems of the type here involved' may be obtained to operate with a minimum glow Voltage of about 50 volts without drawing any energy at the normal operating voltage of the system of about 12 volts, at which voltage such neon lamps act as perfect insulators.

The trouble locating switch 5I which is mounted in the control unit has blade contacts TSI, TS2 connected in series with the conductors 66, 6l leading fromthe control unit to the live protective loop branches. The trouble locating switch 5I is so arranged that when its contact blades TSI, TS2 are moved from the normal oli position to the downwardly shown on position, the contact blades TSI, TS2 connect the live loop wires to the ungrounded side of the high voltage transformer winding 45 through a circuit including resistors 46., 88 which are so proportioned as to supply to the loop wiring a voltage at which the neon indicating la vps will glow if noY trouble condition exists in the respective loop portions. The resistance of the protective loop circuit connected to the relatively high voltage transformer winding 45 is so adjusted that about 14 milliamperes will be supplied to the loop wires in order to burn out any corrosive coating or traces of foreign matter that may be deposited on any open break contacts of the protective loop elements during the protection olf period.

Such trouble locating arrangement eliminates the need for skilled technicians and the long tedious searching for the points of the trouble; and the troublesome point ofthe protective wiring may be quickly isolated and removed. Thus, if on returning to the premises the authorized party, on opening the control unit, nds that the pilot lamp 68v is lighted and indicates that an alarm condition occurred during theV protection on period', and the milliammeter 6I connected in the loop circuit shows that there is an opening in the loop, he moves the trouble locating switch from the off to the on positionv thereby applying to the loop wires the high voltage from the transformer Winding 45 which is suicient for lighting the neon lamp indicators. All the neon lamps connected between the portions of the loop extending between the control unit to the point where the loop is open, will receive sufi'icient voltage and will light up. The remainder of the lamps connected beyond the faulty point will not light up. The first unlighted lamp shows that a fault or break exists in the portion of the protective wiring between the last lighted lamp and the first unlit lamp. If more than one break or open point exists on the system, correction of the next break in the sequence of the loop portion will light up all the lamps until the point of the succeeding break. It is thus possible to quickly locate the trouble points and restore the intact condition of the protective wiring system during which all the neon indicating lamps will light up. This includes the main door break springs which should be closed during the test, or otherwise shunted by a special switch.

The trouble locating arrangement utilizing neon lamp indicators, as described above, will suggest other arrangements for securing similar beneficial results. Fig. 2 shows a modified form of trouble locating arrangement using filamenttype lamps 90 instead of neon lamps connected along the successive portions of a protective Wiring loop of the type shown in Fig. 1 containing a series of loop elements 92, 93, 94, 95, 96, 91, 98 arranged to be connected by the contacts TSI, TS2 of a trouble locating switch to a high voltage transformer winding of the supply transformer so as to light up the lamps 90 connected to successive portions of the loop. In order to prevent the indicating lamps 90 from drawing energy or in any other way affecting the normal operation of the protective system when the trouble locating switch with its contacts TSI, TS2 has been moved to the normal test off position, each lamp is connected in series with a condenser 9| dimensioned so as to prevent the flow of direct current through the filamentary lamps 90, but to provide suficient voltage drop for lighting the lamp when the transformer winding applies to the loop conductors 66, 61 an alternating voltage of about 'l0 volts,

In Fig. 2A is shown a further modification of a trouble locating arrangement of the invention. Instead of a condenser, a rectifier unit IGI, such as a copper oxide rectifier, is connected in series with each indicating lamp 9D between successive portions of the protective loop wiring so that the lamp 90 is lighted up by the relatively high voltage A. C. current supplied to the line. However, the polarity of the rectiflers IUI connected in series with each lamp 90 is so arranged as to prevent fiow of direct current when the loop wiring is restored to its normal protective condition and has applied thereto the relatively low voltage D. C. protective circuit current.

The trouble locating arrangement described above assists also the service men in `determining the location of ground troubles on the protective circuits. Thus, as shown in Fig. 1, if a ground occurs on a point of the live protective lead between the conductors 66, G1, none of theA ndicators will light up, even though all attachments are properly set. The ground condition is located by opening each of the attachments individually and observing the indicating lamp on the preceding attachment or group of attachments. When the ground fault exists in the circuit portion beyond the open attachment the lamps preceding the open attachment will light up because the opening of the attachment isolates the grounded portion of the loop. Should the ground be located in the protective circuit portion preceding the open attachment, no indication will be given by the lamps connected to the preceding portion of the protective circuit.

In setting up and testing the protective system of the type described in connection with Fig. 1, the following procedure is followed:

All the doors, windows and other protective devices on the premises including the main door are closed or locked. Control switch 50 is actuated from the off to its test position by raising only its button |06 to bring contact blades SWI, SW2 from their open to their closed contact positions without actuating contacts SW3, SW4. Key shunt switch 8| is in the closed position in which it was left on entering the premises, and the alarm relay remains energized. The contact unit door is open, and its tamper switch 63 is closed on the back contact leading to resistor |01. As a result, the upwardly shown testing position of contacts SWI, SW2 completes a testing circuit from the positive side of the battery, alarm bell I8, housing lining 2|, tamper contacts 23, control unit contacts SWI, TSI, live protective loop conductor 66 returning live loop conductor 61, resistor 1I, milliammeter 6I, back contact 63 of control door tamper, resistor |01, grounded protective loop Gil, grounded conductor 10 to the outer housing and through closed alarm relay front contacts 25 to the negative side of the battery. The resistance |01 in the testing circuit is so adjusted that when the testing circuit described above is established, the milliammeter 6I gives its normal reading, or, 10 milliamperes, in the practical system described herein. A meter reading less than normal or zero, gives an indication that some contacts lare open or some trouble condition exists on the protective wiring circuit. Thereupon, the trouble locating arrangement is utilized for locating and removing the trouble in the way described above. When all the troubles are removed and all attachments are properly set up and the meter 6| reads properly, the control switch 50 is restored to its normal on position and the control unit is locked. The door or cover of the control unit is arranged to automatically return the trouble locating switch 5| to its normal oli position. While the test is performed, the key shunt switch 8| prevents the alarm relay A from becoming deenergized and keeps the alarm silent during the testing and setting up operations. Furthermore, it permits the opening of the protected main door and the leaving of the premises while the protective system is fully set up without sounding thealarm. When the main door isv finally locked on leaving the premises, the key switch 8| is automatically moved by the lock to its open position establishing the normal protection on circuit shown in Fig. l. As a result, if the door of the premises is locked before properly setting up the protective circuit, the opening of the key shunt switch 8| immediately starts the alarm, since the opening of the key switch contacts deenergizes the alarm relay, unless the protective circuit Was properly set up before leaving the premises.

The features and principles of the invention described above in connection with specific exemplifications thereof will suggest to those skilled in the art other ways for designing and arranging protective systems in accordance with the principles of the invention. It is accordingly desired that the appended claims be given a construction commensurate with the scope of the invention within the art.

I claim:

l. In combination with an electric protectivewiring alarm circuit system having an alarm device and means operative in response to the occurrence of a fault in the system for actuating said alarm device, testing means including means operative upon the occurrence of a predetermined alarm condition for testing the condition of the alarm system a predetermined elapsed period after the occurrence of said alarm condition, and restoring means for restoring the alarm system to normal protective condition in the event the fault condition has cleared in said elapsed period 2. In combination with an electrical protective-wiring alarm circuit system having an alarm device and means operative in response to the occurrence of a fault in the system for actuating said alarm device, testing means including means operative upon the occurrence of a predetermined alarm condition for testing the condition of the alarm system a predetermined elapsed period after the occurrence of said alarm condition, resetting means operative following the occurrence of an alarm condition for restoring the alarm system to normal protective condition upon clearing of the fault condition in said elapsed period, re-establishing means operative to re-establish the alarm actuation condition in response to the operation of the testing means in the event the fault still exists in the alarm system, and means operative to repeatedly actuate said testing and resetting means for successively repeating the resetting and testing operations and for silencing the alarm device after a predetermined number of system testing operations are completed.

3. In combination: an electric protective arrangement having a protective wiring system including an alarm device and operating means operative by a current of a predetermined normal system voltage impressed on said wiring system and sufcient to perform protective functions vvith current of said system voltage and cause actuation of said alarm device upon a predetermined disturbance of said wiring system; said Wiring system having a plurality of protective devices interconnected in a common circuit, indicator means including an indicator element interconnected with each of said devices so as to remain normally substantially de-energized when the protective wiring system is operated by the normal system voltage, and testing means including a current source of a different voltage than said normal system voltage and means for connecting said source to said common circuit for energizing said indicator elements so as to detect faults of said protective Wiring system.

4. In combination: an electric protective arrangement having a protective wiring system including an alarm device and operating means operative by a normal voltage current impressed on said wiring system and sumcient to perform protective functions with current of said system voltage and cause actuationof said alarm device upon a predetermined disturbance of said wiring system; said wiring system having a plurality of protective devices arranged in a common circuit, a gaseous discharge lamp connected in the circuit of each of said devices designed and arranged so as to remain normally substantially cle-energized when the protective wiring system is operated by the normal system voltage and having a striking voltage greater than the normal system voltage for preventing the normal voltage current flowing in said protective devices frompassing through said lamps, and testing means including a source of current supply having a voltage greater than the normal system voltage and means for connecting said source to said common circuit for energizing said indicator ele'- ments so as to detect faults of said protective Wiring system.

5. In combination: an electric protective arrangement having a protective Wiring system including an alarm device and operating means operative by a normal voltage current impressed on saidwiring system and sufficient to perform protective functions with current of said system voltage and cause actuation of said alarmvdevice upon a predetermined disturbance of said wiring system; said wiring system having a plurality of protective devices arranged in a common circuit, indicator means including an indicator element connected in the circuit of each of said devices and designed and arranged so as to remain normally substantially de-energized when the protective wiring system is operated by the normal system voltage, and means including a source of current supply having a voltage greater than the normal system voltage and means for connecting said source to said common circuit for energizing said indicator element so as to detect faults of said protective wiring system, and means including circuit connections for establishing a closed circuit condition between said protective devices and said source for passing suicient current through the devices to burn out corrosive contact connections.

6. In combination: an electric protective arrangement having a protective wiring system including an alarm device and operating means operative by normal voltage current impressed on said wiring system and suiiicient to perform protective functions with said current of said system voltage and cause actuation of said alarm device upon a predetermined disturbance of said wiring system; said wiring system having a plurality of protective devices arranged in a common circuit, indicator means including a lamp and a circuit element connected in the circuit of each of said devices so as to prevent the normal system voltage from passing current through said lamps, and testing means including a source of alternating current supply having a voltage greater than the normal system voltage and means for connecting said source to said common circuit for energizing said lamps to detect faults of said protective wiring system while preventing normal energization of said lamps.

7. In combination: an electric protective arrangement having a protective wiring system including an alarm device and operating means operative by a unidirectional current of a predetermined normal system voltage impressed on said wiring system and sufficient to perform protective functions with said current of said system voltage and cause actuation of said alarm device upon a predetermined disturbance lof said wiring system; said wiring system having a plurality of protective devices interconnected in a common circuit, indicator means including an indicator element and unidirectionally conducting means connected in the circuit of each of said devices and designed and arranged so as to prevent the normal system voltage from energizing said indicator elements, and testing means including an alternating current source and means for connecting said source to said common circuit for energizing said indicator elements so as to detect faults of said protective wiring system.

8.1n combination: an electrical protectivewiring alarm circuit system having energizing means, an alarm device, and means operative to actuate said alarm device by said energizing means when a fault occurs in the system, testing means operative upon the occurrence of a predetermined alarm condition for testing the condition of the alarm system a predetermined elapsed period after the occurrence of said alarm condition, restoring means for restoring the alarm System to normal protective condition in the event the fault condition has cleared in said elapsed period, said testing means and said restoring means being associated with a motor arranged to be energized by said energizing means when said alarm device is actuated, cam means driven by said motor over a predetermined path, and switching means interconnected with said alarm circuit and actuatedby the motion of. said cam to cause said testing means and said restoring means to perform their operation in a predetermined sequence.

9. In combination: an electrical protectivewiring alarm circuit system having an alarm device; means operative to energize and actuate said alarm device when a fault occurs in the system, testing means including a motor and means operative to cause said motor to be energized and operated at a predetermined rate when said alarm device is actuated; cam means driven by said motor to perform a predetermined motion. said testing means including switching means actuated by said cam means and operative to test the operating condition of said system and to restore the normal condition of said system, said switching means being operative to de-energize said motor in the event the fault of said system has been cleared.

HERBERT M. LAFORD. 

